While numerous studies have demonstrated the association
between outdoor exposure to atmospheric particulate matter (PM) and adverse
health effects, the actual chemical species responsible for PM toxicological
properties remain a subject of investigation. We provide here reactive
oxygen species (ROS) activity data for PM samples collected at a rural site
in the Po Valley, Italy, during the fog season (i.e., November–March). We
show that the intrinsic ROS activity of Po Valley PM, which is mainly
composed of biomass burning and secondary aerosols, is comparable to that of
traffic-related particles in urban areas. The airborne concentration of PM
components responsible for the ROS activity decreases in fog conditions,
when water-soluble species are scavenged within the droplets. Due to this
partitioning effect of fog, the measured ROS activity of fog water was
contributed mainly by water-soluble organic carbon (WSOC) and secondary
inorganic ions rather than by transition metals. We found that the intrinsic
ROS activity of fog droplets is even greater (> 2.5 times) than
that of the PM on which droplets are formed, indicating that redox-active
compounds are not only scavenged from the particulate phase, but are also
produced within the droplets. Therefore, even if fog formation exerts a
scavenging effect on PM mass and redox-active compounds, the aqueous-phase
formation of reactive secondary organic compounds can eventually enhance ROS
activity of PM when fog evaporates. These findings, based on a case study
during a field campaign in November 2015, indicate that a significant
portion of airborne toxicity in the Po Valley is largely produced by
environmental conditions (fog formation and fog processing) and not simply
by the emission and transport of pollutants
Is data on this page outdated, violates copyrights or anything else? Report the problem now and we will take corresponding actions after reviewing your request.